• Authors:
    • Menendez, S.
    • Maria Estavillo, J.
    • Gonzalez-Murua, C.
    • Dunabeitia, M. K.
    • Fuertes-Mendizabal, T.
    • Huerfano, X.
  • Source: EUROPEAN JOURNAL OF AGRONOMY
  • Volume: 64
  • Year: 2015
  • Summary: Wheat is among the most widely grown cereals in the world. In order to enhance its production, its management is based on the addition of nitrogen (N) fertilizers. Nevertheless, its application could increase nitrous oxide (N2O) emissions, which effects are very pernicious to the environment, being a strong greenhouse gas (GHG). Regarding GHG, soil processes can also produce or consume carbon dioxide (CO2) and methane (CH4). Nitrification inhibitors (NI) have been developed with the aim of decreasing fertilizer-induced N losses and increase N efficiency. The fact that the application of a NI enhances N use efficiency is a good reason to think that more N should be also available for increasing the grain N concentration of wheat plants. If the application of NI means an increase in N use efficiency, it is plausible to consider that more N would be available, hence, increasing the grain N concentration of wheat. We present a two-year field-experiment to evaluate the influence of the NI 3,4-dimethylpyrazol phosphate (DMPP) on grain yield, grain quality and GHG emissions. Fertilizer dose, with and without DMPP, was 180 kg N ha(-1) applied as ammonium sulfate nitrate (ASN) splitted in two applications of 60 kg N ha(-1) and 120 kg N ha(-1), respectively. A treatment with a non-splitted application of ASN with DMPP and an unfertilized treatment were also included. The splitted application of ASN with DMPP was able to reduce N2O emissions, without affecting yield and its components. The alternative management of a non-splitted application of DMPP was more efficient mitigating N2O emissions, whilst keeping yield and slightly reducing grain protein content. In consequence of the low N2O fluxes from our soils, the EF applied in our region should be lower than the default value of 1% proposed by IPCC.
  • Authors:
    • Masilionyte, L.
    • Sasnauskiene, J.
    • Romaneckas, K.
    • Sarauskis, E.
    • Buragiene, S.
    • Kriauciuniene, Z.
  • Source: SCIENCE OF THE TOTAL ENVIRONMENT
  • Volume: 514
  • Year: 2015
  • Summary: Intensive agricultural production strongly influences the global processes that determine climate change. Thus, tillage can play a very important role in climate change. The intensity of soil carbon dioxide (CO 2) emissions, which contribute to the greenhouse effect, can vary depending on the following factors: the tillage system used, meteorological conditions (which vary in different regions of the world), soil properties, plant residue characteristics and other factors. The main purpose of this research was to analyse and assess the effects of autumn tillage systems with different intensities on CO 2 emissions from soils during different seasons and under the climatic conditions of Central Lithuania. The research was conducted at the Experimental Station of Aleksandras Stulginskis University from 2009 to2012; and in 2014. The soils at the experimental site were classified as Eutric Endogleyic Planosol (Drainic). The investigations were conducted using five tillage systems with different intensities, typical of the Baltic Region. Deep conventional ploughing was performed at a depth of 230-250 mm, shallow ploughing was conducted at a depth of 120-150 mm, deep loosening was conducted at depths of 250-270 mm, and shallow loosening was conducted at depths of 120-150 mm. The fifth system was a no-tillage system. Overall, autumn tillage resulted in greater CO 2 emissions from the soil over both short- and long-term periods under the climatic conditions of Central Lithuania, regardless of the tillage system applied. The highest soil CO 2 emissions were observed for the conventional deep ploughing tillage system, and the lowest emissions were observed for the no-tillage system. The meteorological conditions greatly influenced the CO 2 emissions from the soil during the spring. Soil CO 2 emissions were enhanced as precipitation and the air and soil temperatures increased. Long-term investigations regarding the dynamics of CO 2 emissions from soils during the maize vegetation period indicated that autumn tillage systems affect the total soil CO 2 emissions. The highest (2.17 mol m -2 s -1) soil CO 2 emissions during the vegetation period were observed in the deep ploughing tillage system, and the lowest values were observed (1.59 mol m -2 s -1) in the no-tillage system.
  • Authors:
    • Ramirez-Villegas, J.
    • Parkes, B.
    • Challinor, A. J.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 21
  • Issue: 4
  • Year: 2015
  • Summary: Projections of the response of crop yield to climate change at different spatial scales are known to vary. However, understanding of the causes of systematic differences across scale is limited. Here, we hypothesize that heterogeneous cropping intensity is one source of scale dependency. Analysis of observed global data and regional crop modelling demonstrate that areas of high vs. low cropping intensity can have systematically different yields, in both observations and simulations. Analysis of global crop data suggests that heterogeneity in cropping intensity is a likely source of scale dependency for a number of crops across the globe. Further crop modelling and a meta-analysis of projected tropical maize yields are used to assess the implications for climate change assessments. The results show that scale dependency is a potential source of systematic bias. We conclude that spatially comprehensive assessments of climate impacts based on yield alone, without accounting for cropping intensity, are prone to systematic overestimation of climate impacts. The findings therefore suggest a need for greater attention to crop suitability and land use change when assessing the impacts of climate change.
  • Authors:
    • van der Werf, W
    • Zhang, F. S.
    • Six, J.
    • Cong, W. F.
    • Hoffland, E.
    • Li, L.
    • Sun, J. H.
    • Bao, X. G.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 21
  • Issue: 4
  • Year: 2015
  • Summary: Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4%1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 18486 kg C ha -1 yr -1. Soil organic N content in the top 20 cm was 11%1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 4510 kg N ha -1 yr -1. Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil delta 15N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration.
  • Authors:
    • Terry, R. E.
    • Fernandez, F. G.
    • Coronel, E. G.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 2
  • Year: 2015
  • Summary: The use of alternative N sources relative to conventional ones could mitigate soil-surface N 2O emissions. Our objective was to evaluate the effect of anhydrous ammonia (AA), urea, and polymer-coated urea (ESN) on N 2O emissions for continuous corn ( Zea mays L.) production. Corn received 110 kg N ha -1 in 2009 and 180 kg N ha -1 in 2010 and 2011. Soil N 2O fluxes were measured one to three times per week early in the growing season and less frequently later, using vented non-steady state closed chambers and a gas chromatograph. Regardless of N source, N 2O emissions were largest immediately after substantial (>20 mm) rains, dropping to background levels thereafter. Averaged across N sources, 2.85% of the applied N was lost as N 2O. Emission differences for treatments only occurred in 2010, the year with maximum N 2O production. In the 2010 growing season, cumulative emissions (in kg N 2O-N ha -1) were lowest for the check (2.21), followed by ESN (9.77), and ESN was lower than urea (14.07) and AA (16.89). Emissions in 2010 based on unit of corn yield produced followed a similar pattern, and N 2O emissions calculated as percent of applied N showed that AA losses were 1.9 times greater than ESN. Across years, relative to AA, ESN reduced N 2O emissions, emissions per unit of corn yield, and emissions per unit of N applied, whereas urea produced intermediate values. The study indicates that, under high N loss potential (wet and warm conditions), ESN could reduce N 2O emissions more that urea and AA.
  • Authors:
    • Zhang, F. S.
    • Chen, X. P.
    • Christie, P.
    • Cui, Z. L.
    • Meng, Q. F.
    • Ju, X. T.
    • Gao, B.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 203
  • Year: 2015
  • Summary: The large consumption of groundwater for irrigating winter wheat has resulted in a continuous decline in the groundwater table on the North China Plain in recent decades. Alternative cropping systems have been proposed to substitute for the conventional winter wheat-summer maize rotation system for the sustainable use of groundwater in the future. However, the impact of these cropping systems on net global warming potential (net GWP), and greenhouse gas emissions on the basis of per unit of yield (greenhouse gas intensity, GHGI) is poorly documented. Measurements of greenhouse gases were conducted over a four-year period to gain insight into net GWP and GHGI on a crop rotation scale based on an ongoing long-term field experiment on the North China Plain. The cropping systems investigated include one conventional winter wheat-summer maize system (Chem. W/M) as the control and four alternative cropping systems, namely an optimized winter wheat-summer maize system (Opt. W/M), two winter wheat-summer maize (or soybean)-spring maize system with three crops in two years (W/M-M, W/S-M), and a single spring maize per year (M). Compared with the Chem. W/M control, the grain yields in Opt. W/M increased significantly by 19% while the net GWP, GHGI and fertilizer N decreased by 29%, 40% and 40%, respectively, but still consumed as much groundwater (264 mm yr(-1)) as Chem. W/M. In the two-year rotation cycle fertilizer N, groundwater use, net GWP and GHGI in W/M-M, W/S-M and M declined by 56-70%, 43-63%, 50-58% and 30-50%, respectively, compared to Chem. W/M. Moreover, these cropping systems consumed only 108-159 mm yr(-1) groundwater for irrigation, a value close to the theoretical value of 150 mm yr(-1) to avoid a continuing decline in the groundwater table in this region. However, W/S-M treatment had grain yield reductions of -23% and M treatment had -30%, and only W/M-M maintained grain yields relative to Chem. W/M. We, therefore recommend the W/M-M management package as a preferred option to maintain grain yields together with low GWP and GHGI while mitigating the decline in the groundwater table in areas with a high water deficit.
  • Authors:
    • Gan, Y. T.
    • Cui, H. Y.
    • Yin, W.
    • Yu, A. Z.
    • Chai, Q.
    • Hu, F. L.
  • Source: AGRONOMY FOR SUSTAINABLE DEVELOPMENT
  • Volume: 35
  • Issue: 2
  • Year: 2015
  • Summary: Intercropping is used to increase grain production in many areas of the world. However, this increasing crop yield costs large amounts of water used by intercropped plants. In addition, intercropping usually requires higher inputs that induce greenhouse gas emissions. Actually, it is unknown whether intercropping can be effective in water-limited arid areas. Here, we measured crop yield, water consumption, soil respiration, and carbon emissions of wheat-maize intercropping under different tillage and crop residue management options. A field experiment was conducted at Wuwei in northwest China in 2011 and 2012. Our results show that wheat-maize intercropping increased grain yield by 61 % in 2011 and 63 % in 2012 compared with the average yield of monoculture crops. The intercropping under reduced tillage with stubble mulching yielded 15.9 t ha(-1) in 2011 and 15.5 t ha(-1) in 2012, an increase of 7.8 % in 2011 and 8.1 % in 2012, compared to conventional tillage. Wheat-maize intercropping had carbon emission of 2,400 kg C ha(-1) during the growing season, about 7 % less than monoculture maize, of 2,580 kg C ha(-1). Reduced tillage decreased C emission over conventional tillage by 6.7 % for the intercropping, 5.9 % for monoculture maize, and 7.1 % for monoculture wheat. Compared to monoculture maize, wheat-maize intercropping used more water but emitted 3.4 kg C per hectare per millimeter of water used, which was 23 % lower than monoculture maize. Overall, our findings show that maize-wheat intercropping with reduced tillage coupled with stubble mulching can be used to increase grain production while effectively lower carbon emissions in arid areas.
  • Authors:
    • Hatfield, J. L.
    • Jarecki, M. K.
    • Barbour, W.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 2
  • Year: 2015
  • Summary: The U.S. Corn Belt area has the capacity to generate high nitrous oxide (N 2O) emissions due to medium to high annual precipitation, medium- to heavy-textured soils rich in organic matter, and high nitrogen (N) application rates. The purpose of this work was to estimate N 2O emissions from cornfields in Iowa at the county level using the DeNitrification-DeComposition (DNDC) model and to compare the DNDC N 2O emission estimates with available results from field experiments. All data were acquired for 2007 to 2011. Weather Underground Network and the Iowa State University Iowa Soil Properties and Interpretation Database 7.3 were the data sources for DNDC inputs and for computing county soil parameters. The National Agriculture Statistic Service 5-yr averages for corn yield data were used to establish ex post fertilizer N input at the county level. The DNDC output suggested county-wide N 2O emissions in Iowa ranged from 2.2 kg N 2O-N ha -1 yr -1 in south-central to 4.6 to 4.7 kg N 2O-N ha -1 yr -1 in north-central and eastern Iowa counties. In northern districts, the average direct N 2O emissions were 3.2, 4.4, and 3.6 kg N 2O-N ha -1 yr -1 for west, central, and east, respectively. In central districts, average N 2O emissions were 3.5, 3.9, and 3.4 kg N 2O-N ha -1 yr -1 for west, central, and east, respectively. For southern districts, N 2O emissions were 3.5, 2.6, and 3.1 kg N 2O-N ha -1 yr -1 for west, central, and east, respectively. Direct N 2O emissions estimated by the DNDC model were 1.93% of N fertilizer input to corn fields in Iowa, with values ranging from 1.66% in the northwest cropping district to 2.25% in the north-central cropping district. These values are higher than the average 1% loss rate used in the IPCC Tier 1 approach.
  • Authors:
    • Boddey, R. M.
    • Alves, B. J. R.
    • Batista, J. N.
    • Polidoro, J. C.
    • Jantalia, C. P.
    • Martins, M. R.
    • Urquiaga, S.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 151
  • Year: 2015
  • Summary: The low natural fertility of Oxisols in the Cerrado region makes some crops in this region very dependent on high rates of synthetic N-fertilizers, which are of growing environmental concern as a major source of N2O emissions in agriculture. In a field experiment, we quantified direct N2O emissions and NH3 volatilization (a source of indirect N2O emissions) from surface-applied N fertilizer on a no-till maize (Zea mays L.) crop in Cerrado biome. We used four fertilizers at the rate of 120kgNha-1 as topdress-N (V4-V6 growth stage), which were regular urea, urea+zeolite, calcium nitrate and ammonium sulfate, and a non-topdressed control. The total N losses as volatilized NH3 ranged from 2.2% (calcium nitrate) to 4.5% (urea+zeolite). The N loss as volatilized NH3 from urea was very low (3.2%), with no significant difference between urea+zeolite, ammonium sulfate and calcium nitrate. Significantly, higher cumulated N2O emissions were observed with ammonium sulfate than with the control. No significant differences among fertilizers were found for emission factor (EF), which was 0.20% on average (0.14-0.26%), indicating that use of IPCC default EF (1.00%) would substantially overestimate N2O emission. Free drainage and acidity of Oxisols and occurrence of dry spells, known as 'veranicos', are characteristics of Cerrado biome that may naturally mitigate N2O emissions.
  • Authors:
    • Ekblad, A.
    • Menichetti, L.
    • Katterer, T.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 200
  • Year: 2015
  • Summary: The contribution of different C inputs to organic carbon accumulation within the soil profile in the Ultuna long-term continuous soil organic matter experiment, established in 1956, was determined. Until 1999, C 3-crops were grown at the site, but since then maize (C 4) has been the only crop. The effect of a total of 10 different inorganic nitrogen and organic amendment treatments (4 Mg C ha -1 yr -1) on SOC in topsoil and subsoil after 53 years was evaluated and the contribution from maize roots to SOC after 10 years of cultivation was estimated. Soil organic carbon (SOC) and delta 13C signature were measured down to 50 cm depth. The C content in the topsoil (0-20 cm depth) was 1.5% at the start of the experiment. After 53 years of treatments, the average topsoil C content varied between 0.9 and 3.8% of soil dry weight, with the open fallow having the lowest and the peat amended the highest value. Nitrogen seemed to promote C accumulation in the topsoil treatment effects were smaller below 20 cm depth and only two of the amendments (peat and sewage sludge) significantly affected SOC content down to 35 cm depth. Despite this, penetrometer measurements showed significant treatment differences of compaction below 41 cm depth, and although we could not explain these differences this presented some evidence of an initial treatment-induced subsoil differentiation. Ten years of maize growth affected the delta 13C of SOC down to 22.5 cm depth, where it varied between -25.16 and -26.33(per mil), and an isotopic mass balance calculation suggested that maize C accounted for 4-8% of total SOC in the topsoil. Until less than 2500 years ago the site was a post-glacial sea floor and the 14C data suggest that marine sediment C still dominates the SOC in deeper soil layers. Overall, the results suggest that 53 years of treatments has caused dramatic changes on the stored C in the topsoil in several of the treatments, while the changes in the subsoil is much less dramatic and a small C accumulation in the upper subsoil was found in two of the treatments. The contribution from roots to SOC accumulation was generally equal to or greater than the contribution from amendments. The retention coefficient of root-derived C in the topsoil was on average 0.300.09, which is higher than usually reported in the literature for plant residues but confirms previous findings for the same experiment using another approach. This strengthens the conclusion that root-derived SOC contributed more to SOC than above-ground crop residues.